Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$211.58	5.550%	$223.3227	$223.32	$223.30	$223.30
Purchase #2	$6.76	9.310%	$7.3894	$7.39	$7.40	$7.40
Purchase #3	$157.26	5.709%	$166.238	$166.24	$166.25	$166.20
Purchase #4	$232.92	13.510%	$264.3875	$264.39	$264.40	$264.40
Purchase #5	$55.85	13.483%	$63.3803	$63.38	$63.40	$63.40
Purchase #6	$143.28	10.717%	$158.6353	$158.64	$158.65	$158.60
Purchase #7	$174.76	6.417%	$185.9743	$185.97	$185.95	$186.00
7 purchase totals =	$982.41		$1,069.3275	$1,069.33	$1,069.35	$1,069.30